Starting with the next snapshots dated after this post, textdump support will be in all kernels for full installs.
Embedded systems lack the swap space necessary for dumps to work, so debugging with them will still require switching to a debug kernel
So what are textdumps?
In short, they automatically capture information about a crash: The panic message, backtrace, and other info about the system state at the time of the crash.
For more in-depth detail, see here
After a crash, when your system reboots, you will be left with the textdump data in tar format under /var/crash, like so:
-rw------- 1 root wheel 123904 Jan 27 17:01 textdump.tar.0
If there are multiple textdumps, the number at the end will increment. The highest number (and of course latest date) are always the most recent data.
If asked by a developer, you can submit the whole tar file, or untar the file and copy/paste the individual files into forum attachments. To unpack the tar file on the router, you can do something like this:
[2.0-BETA5][email@example.com]/root(1): mkdir crash
[2.0-BETA5][firstname.lastname@example.org]/root(2): cd crash/
[2.0-BETA5][email@example.com]/root/crash(3): tar xvf /var/crash/textdump.tar.0
[2.0-BETA5][firstname.lastname@example.org]/root/crash(4): ls -l
-rw------- 1 root wheel 5289 Jan 27 17:00 config.txt
-rw------- 1 root wheel 49152 Jan 27 17:00 ddb.txt
-rw------- 1 root wheel 65508 Jan 27 17:00 msgbuf.txt
-rw------- 1 root wheel 16 Jan 27 17:00 panic.txt
-rw------- 1 root wheel 138 Jan 27 17:00 version.txt
Or copy the tar file off with scp and unpack it locally.
The files included in the dump are:
* config.txt - Kernel configuration
* ddb.txt - Captured DDB output (including the backtrace and other helpful info)
* msgbuf.txt - Kernel message buffer, should be roughly equivalent to the system.log file.
* panic.txt - Kernel panic message, if there was a panic
* version.txt - Kernel version string
You may still need to switch to a debug kernel
to get more detail about locks.
Hopefully in the near future, none of this will be necessary :-)